1. Technical Field
This invention relates to a non-contact, optical-based track inspection system including a vehicle for travel on the track and an inspection unit mounted on the vehicle.
2. Description of Related Art
Maintaining proper conditions of rail components of a railroad track is of paramount importance in the railroad transportation industry. Rails of the railroad track are subject to movement and wear due to the passage of trains over the rails, especially with heavy freight trains. Changes in track geometry and cracks are common defects and anomalies created in the rails of the railroad track by the passage of heavy rolling stock over the rails. Conditions of the railroad track greatly impact safety and reliability of rail transportation. Failure or degradation of various rail components, such as cross ties, joint bars, fasteners, switch frogs, and rail fasteners, as well as the rail segments themselves, can cause derailment of a train traveling on the railroad track. Such derailment can cause significant property damage, and injury to passengers and crew aboard the derailed train.
To inspect the railroad track for various anomalies and to ensure that all rail components are in good condition, an optical inspection system may be used for non-contact measurements of the railroad track. Such a system may be mounted under an inspection car and may include optical sensors such as video cameras and lasers. Lasers and lamps are utilized to emit a beam of light across the railroad track. The laser produces a projected line that is substantially straight and extends substantially perpendicular to the surface of the railroad track. Cameras may be mounted at an angle with respect to the beam of light projected from the lasers. As the inspection system moves along the railroad track, the video camera captures images of the railroad track illuminated by the beam of light, thereby acquiring measurements and profiles of the railroad track. Optical inspection systems provide a high level of accuracy but have inherent weather and reliability limitations. In the railroad environment, a clear glass or plastic window of an enclosure containing optical sensors can become contaminated with dirt, dust, mud, grease, and other contaminants that block or obscure an optical path of the optical sensors. Accordingly, the protective window of the optical sensors requires periodic cleaning.
In some cases the inspection car can be stopped and the protective window of the optical sensors can be manually cleaned by an operator. However, this is a time-consuming operation, and is often not possible or desirable due to constraints of the railroad system. On unmanned systems an automatic cleaning system is necessary since manual cleaning is not possible. Other railroad track inspection systems utilize high pressure air to blow off contaminants. However, such a method requires a large air compressor or blower and often is ineffective for heavy dirt and grease particles. A high pressure water spray has also been used for cleaning the protective window of the optical sensors; however, this requires a large water tank with periodic filling of water and anti-freeze. Furthermore, some railroad track inspection systems utilize a windshield wiper to clean the protective window, but this can be ineffective unless used with a cleaning fluid stored in a tank. The windshield wiper also can smear heavy oils and grease.
Accordingly, there is a need to overcome the above disadvantages. There is a need for a device, system, and method for automatically cleaning a protective window for optical sensors to ensure a clear and unobstructed optical path for the optical sensors in a railroad track inspection system.